As males age, they experience a loss of Y chromosomes due to rapid cell turnover, which has significant implications for cancer risk, particularly bladder cancer. A study led by Dan Theodorescu at Cedars-Sinai Cancer, published in Nature, establishes a link between Y chromosome loss and the immune system's ability to combat cancer. The research indicates that this loss allows bladder cancer cells to evade immune detection and proliferate aggressively, increasing the disease's severity and treatment challenges. The findings underscore the importance of early detection and preventive measures for bladder cancer in older males, as well as the need for further investigation into the Y chromosome's role in other cancers and overall health. This research highlights the Y chromosome's dual role in defining male characteristics and enhancing cancer immunity, urging men to be vigilant about their health as they age.